Metastasis to the thyroid from pulmonary adenocarcinoma : appearing as a solitary benign looking thyroid mass on US

Abstract

A 62-year-old woman presented with lung cancer, and underwent FDG-PET/CT for staging. On PET/CT, thyroid mass with increased FDG uptake was incidentally found. Ultrasonography revealed a well-defined heterogeneous hypoechoic mass without microcalcification in right lobe of thyroid, appearing as benign thyroid mass. Subsequently, the thyroid mass was confirmed as metastasis by fine needle aspiration biopsy for staging. Thyroid metastases are uncommon, and may show sonographic findings of primary thyroid carcinoma except microcalcification. We report a case of thyroid metastasis mimicking solitary benign thyroid mass on ultrasonography.